5 years ago

Blacksburg, Virginia - Virginia Tech

Blacksburg, Virginia - Virginia Tech

Overall, nitrate

Overall, nitrate accumulation was affected by both N rate and N source. Nitrate levels, on average, declined with each subsequent harvest. This might be due to the fact that all N was applied at planting and not split. Dangerous levels of nitrates were seen at the second harvest only at the 135 kg N ha -1 rates. In general, BL produced much safer levels of nitrate accumulation than AN. This was due to the N from BL being released at slower rates, thus preventing the rapid uptake by the growing plant. In some instances, dangerous levels of nitrate accumulation were reached at both the 0 and 45 kg N ha -1 , but on average these rates were safe. The 90 and 135 kg N ha -1 rates often resulted in high levels of nitrate in the teff, and should be heavily monitored when fed to livestock. Summary and Conclusions Seasonal accumulation of biomass ranged from 1478 to 8875 kg DM ha -1 over all years, locations, N rates, and N sources with an average production of 4550 kg DM ha -1 . Average CP values over year, location, N rate and N source came in at 130 g kg -1 with ADF at values of 370 g kg -1 and NDF at 650 g kg -1 . Average TDN values reported were 590 g kg -1 . All of these quality factors can serve wide classes of livestock. In general, biomass production and forage quality went down per harvest. Overall, our results shows that teff can be of value as a forage crop to fill in the mid-summer forage production gap often created by the low productivity of perennial cool-season grasses. The study also showed that Teff can be adapted to a wide range of climatic zones and conditions. Teff‟s performance during the 2010 growing season, which was drier and hotter than the previous year and the historic average, show its potential to be used as drought tolerant species. Quality data showed no clear response to either N rate or N source. Biomass yield and nitrate accumulation show the main response to both N source and rate 61

treatments. Nitrate accumulation at dangerous levels was evident with ammonium nitrate single application at higher rates. In general, broiler litter produced much lower levels of nitrates than the ammonium nitrate. Generally, the N rate that resulted in the maximum biomass production and safe nitrate accumulation in teff regardless of source was the 45 kg N ha -1 rate. Overall, our study shows teff to be a viable alternative for mid-summer forage production. The quick establishment and recovery after cutting prove it to be a usable emergency crop to fit into a grazing system. The lower end N requirement verifies it as low input crop compared to other summer annuals. This study also advocates teff‟s ability to cope with highly variable environmental conditions (temperature and rainfall), showing little variability in yield and quality data between two very different growing seasons of 2009 and 2010. Nitrate accumulation could be a potential problem, and therefore high (90+ kg N ha -1 ) single N application rates should be avoided. 62

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